UK exhaust mod
 

It is called the "UK Exhaust Mod" because it was first done by an owner in the UK and then posted onto this forum to share the unique process and unique result.

The car in the King Motorsports link, above, is mine (note my last name on the dyno report). I opted for the 25mm bypass which King so expertly installed. It gave me exactly the sound that I was looking for to better "read the engine" on the track. It turned out that there was a minor increase in performance on the dyno but not enough to make this a compelling modification. The dyno was done while I was without FI. I was then between my old Comptech SC and waiting for my SOS SC. I do not have comparative dyno runs with FI.

However, it seems that most folks install a larger bypass in the 44mm ± range.

Isn't the UK mod also done on a lot of other cars? I think I saw an article on the Z4 or something being able to do it as well. And I think a lot of 911s... I believe the bypass pipe on mine is much larger. It is almost the diameter of the pipe leading to the muffler itself! Will take pics today, as my wheels are off and it's easy to see at the moment.

Seen a lot of crap UK mods and quite shocking workmanship,so if you don't have a quality fabricator,leave it alone..
Got some 25mm pipe,but not yet installed

Pic here:
https://cimg5.ibsrv.net/gimg/www.s2k...7802cfaeba.jpg

Can I ask where you got it done? I'm itching to get this done and it'd be nice to go to a place that already knows how to do it.

I traded my Invidia exhaust to someone in Bay Area (back when I lived there) so he had it done locally down there. Not sure where a good place to do it around here might be.

Any number of bypass pipe diameters will work. Bigger = Louder. Hard, though, once the welding is done to go to a quieter version.

-- Chuck